The Kinesiology and Biomechanics of the Freestyle Stroke (Part 2)

In the last post, we began to explore the human body and how it contributes to the freestyle stroke. We looked at the trapezius, the rhomboids and the serratus anterior and learned what functions they serve in our daily lives.
Today, we continue that journey.
As we explore the other muscles that contribute to the last two stages of the freestyle stroke.
 

mid pull throughLATE PULL-THROUGH

The late pull-through is the third step of the freestyle stroke. It is the phase where your arm is almost finished pulling through the water.
“Just after the catch, the pectoralis major fires and adducts and extends the humerus while internal rotation is balanced by the antagonistic external rotation of the teres minor.”

pectoralis_major (1)5. PECTORALIS MAJOR

The pectoralis major is a thick, top layer muscle that lays right on your chest. It is shaped somewhat like a large clam shell or a fan.
The pectoralis major has four main functions. All of which involve moving the shoulder joint.

6. TERES MINOR

Teres_minor_muscle_back3The teres minor is a small, narrow, muscle that is deep to the pectoralis major. It is shaped like a long and skinny rectangle. The teres minor is considered a rotator cuff muscle. It helps keep the arm attached to the shoulder blade since it is a ball in socket joint.
It’s main job is to aid in rotating and lifting the arm outward away from the body and across the body. It also assists in any other arm movements that occur at the shoulder as an assisting muscle.

the recoveryTHE RECOVERY

The recovery is the last step of the freestyle stroke. It is the phase where your arm is finished pulling through the water but before you start your next stroke.
“The latissimus dorsi fires in concert with the subscapularis from the mid pull-through until
the beginning of recovery. The deltoid and supraspinatus are the prime movers through
recovery.”

Latissimus_dorsi7. LATISSIMUS DORSI

The latissimus dorsi is a large, flat, broad muscle. It is mostly a top layer muscle (the trapezius overlaps it just a little bit).
The latissimus dorsi helps you extend your arm out and back in, flex your arm from an extended position, and rotate your arm in towards your body at the shoulder joint.  It also helps you flex and extend your lower back and it can influence downward rotation in the shoulder blade.

subscap8. SUBSCAPULARIS

The subscapularis is a small, triangular shaped muscle that lies on the back side of the shoulder blade (inside the body).
One part of this muscle’s role is to protect and stabilize the arm (preventing displacement). But the main job of the subscapularis is to rotate the arm inward toward the body. Also, when the arm is raised above the head, the subscapularis helps pull the arm down in front of the body.

deltoid9. DELTOID

The deltoid muscle sits on the corner of the shoulder and is kind of shaped like a triangular bowl.
The deltoid is in charge of lifting your arms up straight in front of you. The scientific name for this term is abduction. Which is defined as “a type of movement which draws a limb away from the median plane of the body.”
It’s easy to remember if you think of the other common meaning of abduction, which is to be drawn away from planet earth by aliens. Both meanings refer to being drawn away.

superspinatus10. SUPRASPINATUS

The supraspinatus is a smaller, skinny, muscle that is shaped like a triangle and sits on the top of your shoulder.
The primary role of the supraspinatus is lifting the arm up and out from the side of your body (another form of abduction). Basically it’s role is very similar to the deltoid with one exception.
Deltoids help move the arm up towards the front and the supraspinatus helps move it up and to the side.
 

Isn’t the human body amazing?

muscle swimsuitIsn’t it crazy?…
How all these completely intricate, expert machines operate in our bodies day in and day out?
Muscles enable us to perform literally every swimming stroke and all other physical actions we make throughout our entire lives.
And most of us don’t even know what these muscles’ names are…
Do you have any other amazing facts about the human body to share? If so, please tell us in the comment section.
 
 
 


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